The term allo stasis has been introduced in the chapter “Allostasis: A new paradigm to explain arousal pathology, In Fisher, S., Reason, J. (Eds.) Handbook of Life Stress, Cognition and Health, John Wiley and Sons, New York, (1988), p 629-649”. Hemostatis emphasizes that the body's internal environment is held constant by the self-correcting (negative feedback) actions of its constituent organs. Allostasis emphasizes that internal milieu varies to meet perceived and anticipated demand. In other words, allostasis refers to the active process by which the body responds to daily events and maintains homeostasis.
In the paper “Central effects of stress hormones in health and disease: Understanding the protective and damaging effects of stress and stress mediators, B. S. McEwen, European Journal of Pharmacology 583 (2008), p 174-185” the central effects of stress hormones in health and disease are described. Stress begins in the brain and affects the brain, as well as the rest of the body. Acute stress responses promote adaptation and survival via responses of neural, cardiovascular, autonomic, immune and metabolic systems. Chronic stress can promote and exacerbate pathophysiology through the same systems that are dysregulated. The burden of chronic stress and accompanying changes in personal behaviors (smoking, eating too much, drinking, poor quality sleep; otherwise referred to as “lifestyle”) is called allostatic overload. It is clear that chronic stress is not healthy.
Quantification of stress is for example described in WO 2006/090371 A2. WO 2006/090371 A2 discloses a system and method for monitoring one or more physiological parameters of a user. The system comprises one or more wearable sensor modules sensing the one or more physiological parameters. One or more transmitters wirelessly transmit signals indicative of values of the one or more physiological parameters to a mobile monitor. The mobile monitor comprises a first processor processing the signals received from the transmitter in real time using expert knowledge. A device provides one or more indications of results of the processing. In an embodiment the first processor is configured to calculate from the first signals one or both of the parameter indicated of an arousal state of the user and a parameter indicative of an emotional state of the user. Further, the calculation of the parameter indicative of an arousal state of the user can include calculating a score of a sympathetic or parasympathetic activity of the user using an algorithm based on anyone or more of the user's electrodermal activity, heart rate, EDA variability, and HR variability.
It is currently becoming more and more important to not only quantify stress, but to actually balance stress (e.g. due to a more demanding lifestyle or faster pace of life). US 2009/0264711 A1 discloses a method and apparatus for behavior modification. During operation an apparatus learns what context causes desired and undesired physiological parameters and then coaches a user to be aware of context causing undesired behavior and avoid future occurrences. The apparatus may then recommend behavior modification prior to the parameter reaching elevated status. Because an individual will be warned when situations exist that will cause undesired physiological parameters, the apparatus will suggest to the user a method to alleviate the situation, for example, substituting an activity or context that creates desired physiological patterns. The user will then be able to take appropriate steps to alleviate the situation.
However, a system with a real-time assessment of the cumulative stress load in terms of the deviation from allo stasis, and the danger of allo static overload, is presently not available. Therefore, there is a need to provide an improved system for estimating the mental balance of a user.